This invention relates to new compositions and methods for cleaning textile substrates, especially carpet and upholstery fabrics. More particularly, this invention relates to liquid compositions that contain absorbent particles in a flowable fluid dispersion, which dries to a soil ladened powder, that can be removed by vacuum, brushing, and/or laundering methods. Previous efforts in this area show a continuing need to improve four important features of the textile substrate, especially of the carpet or upholstery cleaning process. These features include: (a) the convenience of applying a cleaning composition, (b) the cleaning efficiency of the cleaning composition, (c) the length of time a cleaned textile is wet, and (d) the reduction of the resoil rate caused by residual surfactant.
The methods of cleaning of textile substrates may be generally placed into three categories. The first category involves the immersion of the textile into a cleaning solvent followed by agitation and removal of soiled solvent. In this case, water is the preferred solvent, provided that the fiber and/or textile substrate is stable to it. Typically, the additives used to facilitate soil removal by the solvent are surfactants, ionic chelators, and pH adjusters. Other minor ingredients are generally included to enhance the cleaning process. These include fragrances, bleaches, optical brighteners, and anti-resoil ingredients. For example, U.S. Pat. Nos. 5,786,317; 6,010,539; and 5,714,449 to Donker, et al., describe a non-aqueous liquid cleaning composition containing solid particles suspended by the use of hydrophobically modified silica particles. This composition is designed for liquid detergent concentrates for washing machine applications and the particles are active bleaching agents. If the textile is small, this process generally uses standard washing machines or dry cleaning machines to clean the textile. If the textile is large or physically affixed to an object, this process uses portable liquid applicators and vacuum retrieval of the soiled fluid. This method, often referred to as “hot water extraction,” applies a substantial amount of water based cleaning solution to the textiles, such as a carpet or upholstery, and uses vacuum extraction to partially remove the soil and surfactant laden cleaning solution. This process typically leaves a residual surfactant on a carpet that attracts dirt to its surface and provides a wet textile that can take many hours to completely dry. The water in the composition is known to cause rust stains if it comes into contact with iron-containing objects, as well as, to provide enhanced growing conditions for mold and other microorganisms. These deficiencies are substantially overcome by low water, powdered cleaning compositions.
The second general category of methods for cleaning textiles involves applying foam-containing solvents and surfactants to the textile followed by agitation with a brush or damp mop. Typically, the applied foam collapses after contact with the textile, and the spots and soil become less visible. While the appearance on the surface of the textile, such as a carpet, is improved, very little dirt or surfactant is actually removed. The main advantages of this method are the ability to use household tools and equipment and the rapid cleaning cycle. Canadian Patent No. 985113, assigned to Unilever Limited, shows a variation on this wherein a non-scrub foam, which contains soil retardant particles, is applied to the carpet. These soil retardant particles remain as a residue on the carpet after the other components of the foam are removed by vacuuming. While this method can be used to improve the appearance of a carpet, it is not an effective method of removing dirt and furthermore, it leaves a substantial residue on the carpet.
The third general category of methods of cleaning textiles involves applying a solid composition that contains a solvent and a cleaning surfactant to the textile followed by agitation. Typically, the solvent is allowed to evaporate and the soiled particles are retrieved with a vacuum cleaner or removed by brushing. Powdered cleaning compositions, or other dry-type cleaning compositions, generally contain, in addition to a liquid component and surfactant component, any of a rather wide variety of both natural and synthetic solid particulate materials. Natural solid particulate materials include, for example, buckwheat flour (see U.S. Pat. No. 2,165,586 to Studer), wood flour, and diatomaceous earth of specific particle size and low bulk density (see U.S. Pat. No. 3,418,243 to Hoxie). Synthetic solid particulate materials include, for example, polymeric materials such as polyurethanes, polystyrenes and phenolformaldehyde resin particles, as disclosed, for example, in French Patent No. 2,015,972. Several examples of powdered cleaning compositions are discussed below.
U.S. Pat. No. 4,013,594 to Froehlich, et al. discloses a powdered cleaning composition that contains, as a major component, solid polymeric urea-formaldehyde particles and a solvent component which may be chosen from water, high boiling hydrocarbon or chlorinated hydrocarbon solvents, aliphatic alcohols and mixtures of such compounds.
U.S. Pat. No. 4,108,800 to Froehlich discloses a semi-dry powdered cleaning composition which further contains polyethylene glycol as an aid to prevent the adherence of fine particles to the fibers being cleaned. This reference further describes the visual problem of “frosting” that occurs when small particles are formed from particle to particle attrition as a result of agitation, such as brushing.
U.S. Pat. No. 4,194,993 to Deal discloses a process for making a powdered cleaning composition which includes the steps of polymerizing urea and formaldehyde in acidic solution to form particles of a desired size, centrifuging the particles, blending polyethyleneoxide into the polymer, and spraying a fine mist of detergent solution onto the polymer mass as it is blended.
U.S. Pat. No. 4,434,067 to Malone, et al. discloses a powdered cleaning composition that contains, in addition to a particulate polymeric material such as urea formaldehyde, an inorganic salt adjuvant and an aqueous or organic fluid component. The Examples and the Tables illustrate that the maximum content of fluid in these powdered cleaning compositions as 40% of the total composition. They further describe the formation of pastes and non-flowable solids when the liquid level or the inorganic salt adjuvant component represents too high a proportion of the total composition.
U.S. Pat. No. 4,802,997 to Fox, et al. discloses a polymer gel cleaning composition that may be sprinkled on a carpet wherein the polymer is insoluble in water yet highly swellable with water. This composition is sponge-like in that it is capable of ejecting solvent under mechanical pressure or brushing and then reabsorbing the solvent when the mechanical pressure or brushing is removed. The pea-sized particles can be removed by vacuuming, even if the solvent has not yet evaporated. The polymers suitable for hydrogel formation can absorb 0.3 to 300 times their weight in water. The swollen gels can be blended with calcium carbonate or wood powder to improve flow characteristics.
U.S. Pat. No. 4,659,494 to Soldanski, et al. describes a cellulose powder containing dry carpet cleaner with reduced dusting, particularly if the carpet cleaner did not contain added surfactant.
U.S. Pat. No. 4,908,149 to Moore, et al. discloses improved carpet cleaning compositions that include acid dye stain blocker additives. These compositions range from particle free solutions to dry-type powders with a minimum of 30% solid particle content.
U.S. Pat. No. 4,873,000 to Weller discloses a powdered freshening and deodorizing composition for carpets. The composition contains inorganic salts in combination with aluminum silicate clay to improve vacuum retrieval. The composition further contains a maximum of 4% liquid comprised of fragrance and organic agglomerating agent.
EP 1,063,282 B1 to Lang, et al. discloses a cellulose-based, porous, particle gel carpet cleaning composition in combination with water and alcohol. This composition remains in the gel state even in the presence of an 80% water and alcohol mixture.
U.S. Pat. No. 5,783,543 to Fleckenstein discloses a scatterable powdered cleaning composition incorporating viscose sponge flakes from 3 to 10 mm in length. The improved composition results in less disruption of the carpet fibers due to the brushing process.
EP 1184449 to Gagliardi, et al. describes a solid cleaning composition with low water content that is particularly useful for cleaning wet spills. The composition incorporates water swellable polymers and anhydrous salts to absorb liquid and turn wet spills into powders that can be removed by vacuum cleaners. The cleaning of wet spills by conventional powdered cleaning agents is problematic due to the potential to form pastes that are not vacuum retrievable.
U.S. Pat. No. 6,569,210 to Chao, et al. describes a novel fabric cleaning method whereby soils are treated with a particulating chemical, such as a colorless sulfonated dye site blocker, to generate particles that are then removed by gas jet interaction.
U.S. Pat. No. 6,010,539 to Pesco discloses a modern example of cleaning compositions for hot water extraction systems. This composition is free of organic solvents and contains water, detergent builders (such as sodium tripolyphosphate), EDTA, non-ionic surfactants, stain soluble resist polymers (such as methacrylic acid salts) and a fluorosurfactant.
There have been a few previous attempts by others to create textile cleaning methods and compositions that use liquid or paste systems with particles and solvent. These are briefly described below.
U.S. Pat. No. 3,910,848 to Froehlich et al. discloses a cleaning formulation that comprises a halogenated solvent and urea formaldehyde polymer particles as major components. The composition further contains small amounts of an antistatic agent and an anti-settling agent and optionally, a chlorofluorinated propellant for aerosol applications. The high liquid density of the halogenated solvent helps to suspend the particles but its human and ecological impact make it undesirable for consumer use. The reference fails to recommend or suggest the use of water as a solvent.
U.S. Pat. No. 3,956,162 to Lautenberger describes a thixotropic cleaning paste for cleaning non-horizontal surfaces. The paste contains particles with oil absorption values above 90, minor amounts of water, both low and high boiling hydrocarbon or halogenated hydrocarbon solvents, surfactant, silica (to provide thixotropic flow characteristics), and various other additives. This composition dries to apparently free flowing particles that can be removed by vacuuming or brushing. This thick composition is not suitable for spraying and contains either the undesirable flammability of hydrocarbon solvents or the undesirable health effects of halogenated solvents.
U.S. Pat. No. 4,685,930 to Kasprzak describes a cleaning method of applying liquid cyclic siloxane solvents to soiled textiles and then removing the solvents and dirt by blotting with absorbent paper towels. Alternatively, a solid mixture of cyclic siloxane solvent and an absorbent material selected from mineral particulates, organic particulates, and synthetic porous polymers may be applied to the soiled textile and subsequently removed by brushing or vacuuming. Method claims directed to absorbent particles are limited to cyclic siloxane solvents and stains derived from oil, grease, or sebum.
U.S. Pat. No. 5,259,984 to Hull describes a water-containing polymer cleaning solution that contains a volatile alcohol and a polyamine. This gel or lotion-like solution is spread over the carpet or upholstery, allowed to thicken by evaporation, and then rubbed into soft absorbent polymer gel balls that absorb dirt which may then be removed by brushing or vacuuming. This method seems well suited to rinse-free cleaning of hands, where rubbing and brushing is effective, but is of questionable utility on textile products where the gel may be entrapped within the textile structure and where a fully dried polymer solution may prove intractable.
Finally, in US Patent Application No. 2003/0092589 and related US Patent Application No. 2003/0109399 to Todini et al. a liquid nanolatex and surfactant containing composition and method of cleaning carpets is disclosed. Due to the small size of the nanolatex particles, the particles form suspensions in water. It is further disclosed that upon drying, the nanolatex particles agglomerate and can be removed by vacuum methods. The soil removal index in the table on page 7 of both applications shows several examples of cleaning compositions without illustrating a clear advantage over vacuuming alone.
Thus, as is illustrated by the previous efforts of others, the use of solid cleaning agents for carpet or upholstery has been recognized as the superior method of cleaning. Its low water content allows both for rapid drying and safe cleaning of even expensive wool carpets. The hand application (i.e. sprinkling and spraying methods) and brushing followed by retrieval using the household vacuum cleaner requires no specialized machinery. The particles absorb both sticky soils and residual surfactants so that the textile remains cleaner much longer. In addition, solid cleaning agents have been established to effectively remove allergens, while not promoting the growth of micro-organisms.
There are, however, limitations to the use of solid cleaning agents. The solid cleaning agents may be characterized by the classical Critical Pigment Volume (CPV) effect. The CPV is also known as the oil value, which may be determined by ASTM D281 and which is described, for example, in U.S. Pat. No. 3,956,162 to Lautenberger. To remain a flowable powder, the maximum liquid content is restricted to below the CPV. For particles of a certain shape, the CPV is the volume between particles filled with air. As the air is displaced by a fluid, the flow properties of the powder are reduced until, at the CPV, all the particles are surrounded by liquid. At that point, the mass has the consistency of putty. If more fluid is added, the putty gradually thins until a paint-like dispersion is generated. The practical problem of prior art solid cleaning compositions is that when wet spills are cleaned with powdered cleaning agents, it is possible to generate a paste consistency that, when brushed, does not remain free flowing. This creates a spot that is very difficult to remove. In addition, if brushing occurs at the thick dispersion or paste stage the particle size can be mechanically reduced by particle to particle attrition. Particles having a particle size of less than about 5 microns are held very tightly by electrostatic force and are very difficult to remove by vacuum cleaners. This also leads to an observable residual spot of cleaner on the textile. Therefore, there is the need to provide a solid containing cleaning composition that avoids the practical side effects of the Critical Pigment Volume.
Another limitation of powdered cleaning agents falls into the area of consumer and market perception. Consumers have continued to greatly prefer hot water extraction due to their perception that water and soap are needed to really clean surfaces. Most consumers bathe, clean clothes, clean dishes, and clean hard surfaces with soap and water. There is, therefore, a need to provide a water and soap like cleaning agent without the negative properties of rapid resoil, promotion of microbial growth, and water damage to expensive carpets and other textiles.
Another limitation of powdered cleaning agents and other prior art cleaning methods is the number of steps required to complete the cleaning cycle. For example, the procedure for using the Capture® dry cleaning product, available from Milliken & Company of Spartanburg, S.C., includes the steps of: (1) applying a water based premist solution to the carpet, (2) broadcasting the Capture® dry cleaning composition, (3) brushing the cleaning the composition into the carpet, (4) allowing the product to dry for 30 minutes, and (5) retrieving the soil laden powder using a vacuum cleaner. In comparison, the hot water extraction cleaning process preferred by consumers includes the steps of: (1) vacuuming and removing obstacles and furniture from the area to be cleaned, (2) alternating between applying detergent fluid to the carpet and vacuum extracting the soiled fluid, (3) alternating between applying rinse water and removing soiled rinse water by vacuum extraction, (4) allowing the wet carpet to dry, and (5) returning the removed furniture. Thus, there is a need to provide a cleaning composition and a cleaning method that allows fewer steps.
In summary, there is a need to provide a water-based liquid cleaning composition that dries much faster than hot water extraction systems, that does not exhibit the negative effects of Critical Pigment Volume, that does not require specialized machinery, that provides vacuum retrieval of sticky dirt and residual surfactants, that exhibits reduced resoil rates, and that provide s reduced number of steps in the cleaning cycle.